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Adding to GigE

This Tech Tip is designed to explain some of the additions in the GigE Vision
marketplace that have added to the capabilities of GigE Vision cameras.

Gig E Vision
The main features of GigE Vision
have been covered previously, but as a quick recap some of the points of
note
are:

Long cable lengths –
upto
90m between links with the capability to use fibre
-
optics to go much further
between links
, all this with standard consumer components.

Network topologies
–
one
camera
to one
PC
, many
came
ras
to one
PC
and one
camera
to many
PCs
–
ethernet
-
based transmissio
ns has opened possiblities that were not feasible with framegrabber
-
based
systems and gone much further than was possible with USB and Firewire
-
based systems.

Self-
describing cameras
–
Genicam
means that a device
must describe itself to a
connecting PC by
means of an xml file. This replaces the need for conf
iguration or camera files, for example for describing
the format that data streams fr
o
m a camera.
Power over Ethernet
PoE (Power over Ethernet) is a
standard consumer technology that allows upto 15.4W of DC power
without
sacrificing the cable
-
length capabilities of GigE
.
PoE
-
enabled
G
igE
camera
include
IDS uEye CP cameras and
optionally
Stemmer Imaging
’
s
CVC GE cameras and the
AVT Mant
a
and GT
ranges
. The
advantage is that with
a PoE
-
enabled NIC it is only ne
cessary to run a single cable to the camera.

Since the advent of Gigabit ethernet cameras, the general advice is to use Intel Pro cards as these offer the
most performance options. However, Intel
-
branded cards
do not have PoE capabilities
, but Intel chipsets are
available in third
-
p
arty
cards whic
h do impleme
ent
PoE, such as ADLINK
’
s
GIE62+ and GIE
64+
cards
(two and
four channel, re
s
pe
c
tively)
.

Processing Images from GigE S
ources
The possibilities offered by GigE for large numbers of cameras per PC c
an quickly make processing power the
bottleneck
. For colour
(Bayer)
cameras
that are close to th
e GigE bandwidth limit
, su
ch as DALSA
’
s
high
-
speed
Genie HC range
, even Bayer processing can lead to
significant processing overheads. In light of this Silicon
Software has a range of GigE Vision
framegrabbers to reduce the burden. At the lower end of the scale are the
A
-
series boards, these are delivered with va
rious on
-
board capabilites such as Bayer conversion, look
-
up tables
to improve contrast, white balancing, digital I/
O
and filtering
–
all
with minimal CP
U interaction. These boards
have 4 chan
nels and are available with PoE and can transfer upto 760MB/s (remember that Bayer conversion
multiplies the amount of data
from a camera
)
.

For higher proce
ssing requirements, Silicon Software has it
’
s
V
-
series boards. These have a user
-
programmable FPGA (su
p
porting Silicon Software
’
s
Smart Applets and Visual Applets programming interfaces)
as well as twice as much on
-
board memory as the A
-
series boards
. These are designed to massively offload the
CPU from vision proc
essing tasks, for example the creation of 3D data from laser sheet
-
of
-
light syste
ms or
processing that must be c
arried out in a
deterministic time such as
particularly high
-
speed or high
-
throughput
systems. If the standard
board
’
s
FPGA is
not sufficient it isi also possible to add modules to
extend the
hardware resources of the board. Once again digital I/O is built into the board, allowing it to work directly with
the FPGA design if requ
ired.

GigEVision 2.0

At the time of writing, th
e
r
elease of G
igE Vision 2.0 is imminent. This brings further feature
-
support to GigE
Vision,
including

Firewall traversal
, where a small amount of
data is returned to the camera to show that the connection
to the camera is a two
-
way connection, rather than a malicious attack.

IEEE 1588
Precision Time Protocol
, where each device uses a synchronise
d
clock
(synchronised in
terms of both time and frequency).